This invention relates to a finger irregularity information input apparatus for inputting irregularity information as information indicative of features of an individual finger, and an individual-identifying apparatus for identifying an individual, using the finger irregularity information input apparatus.
Recently, much attention has been paid to individual-identifying apparatuses for identifying whether or not to-be-identified persons are registered ones. These apparatuses are used for the purpose of, for example, managing members who enter or leave important institutions.
Identification of individuals can be performed by various methods. One is to identify individuals from the pattern of the overall finger. For example, Japanese Patent Application KOKAI Publication No. 2-178777 discloses a method for optically picking up an image of the overall finger, and using, as finger characterizing information, an addition signal obtained by adding pixel values of the image in a direction perpendicular to the longitudinal direction of the finger to thereby perform identification. This method, however, requires an optical system, which limits a reduction in the size of the identifying apparatus.
To solve such the limit, Japanese Patent Application KOKAI Publication No. 7-168930, for example, proposes a method for using, instead of an optical system, a linear electrode array which comprises a plurality of linear electrodes extending at regular intervals in a direction perpendicular to the longitudinal direction of a to-be-identified finger. In this method, resistance values between adjacent linear electrodes obtained while the finger presses the linear electrode array are sequentially read and synthesized into a signal, which is used as information indicative of features of the finger.
However, in the individual-identifying apparatus disclosed in Japanese Patent Application KOKAI Publication No. 7-168930, identification information on finger features is extracted by measuring the surface electric resistance (DC impedance) of a finger. Therefore, the information is influenced by the surface state of the finger, for example, whether or not the finger is moist. This means that the individual identifying performance of the apparatus may well degrade depending upon the finger surface state.